Bug 502687 - GCGraphBuilder::AddNode crashes on OOM. Patch by mrbkap, r=dbaron, a=dveditz.

git-svn-id: svn://10.0.0.236/trunk@259382 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/xpcom/base/nsCycleCollector.cpp

@@ -1283,6 +1283,9 @@ GCGraphBuilder::AddNode(void *s, nsCycleCollectionParticipant *aParticipant
                        )
 {
     PtrToNodeEntry *e = static_cast<PtrToNodeEntry*>(PL_DHashTableOperate(&mPtrToNodeMap, s, PL_DHASH_ADD));
+    if (!e)
+        return nsnull;
+
     PtrInfo *result;
     if (!e->mNode) {
         // New entry.